Help - Narrow wide chainring on old road bike

[ilcaccillo]

Hello, everyone
I'm new to the forum, thanks in advance for your help.

I have my beloved bike that was from father. This bike was restored some years ago and new parts were fitted by a mechanic that is far from my hometown nowadays.

It rides very nice, but as there's no front derailleur, the chain is constantly jumping off from the front chainring.
Normally with a bump, or sidewalk, the chain jumps of.

I was thinking in installing a "Narrow wide chainring" as it's recommended by a lot of people in bikes with no front derailleur, but the system that I have installed is completely different than the chainrings I see for sale and also in the youtube videos installation:

I don't have this 4 holes for screws in my crankset

And I dont know if this type will work with my crankset setup and crank Arms:

Here is the Cranset system, bolts and crack arm I have at the moment and maybe it's something that is limited to this type of bike, and it's old, I dont know,
But could you please advice my on what Narrow wide chainring could I use with my system? or if I need to buy a new system as if it's possible to install a new system in this bike?

Thank you so much for your kind help
Best regards

iL

 

[figbat]

Another option is a chain guide, like this.

 

[Ajax Bay]

a chain guide,

I mended a chain on a 1x today (not mine) and the chain seemed well controlled by one of those. Seemed well designed/manufactured. Much cheaper option.

 

[ilcaccillo]

Another option is a chain guide, like this.

Thank you so much figbat, I know the chain guide option, but for the price and overall I prefer to have a "narrow wide chainring" installed.
The guide will help the problem, the "narrow wide chainring" will solve the problem.

Even if I have to change the crankset and crankset arm completely I don't mind the extra expense.
Although if it's possible to install the narrow wide chainring with the present crankset that would be preferable
Thank you so much

 

[figbat]

I mended a chain on a 1x today (not mine) and the chain seemed well controlled by one of those. Seemed well designed/manufactured. Much cheaper option.

I have one on my home-brew gravel bike. Admittedly I also have a narrow-wide chainring. Never dropped a chain.

 

[ilcaccillo]

If anyone could recommend me what should I buy or how could I adapt narrow-wide chainring in my bike that would be great.

Thank you so much

 

[Ajax Bay]

Another option is a chain guide, like this.

recommend me what should I buy

Listen to @figbat: "a chain guide, like this." (click on 'this'!)
As a complete aside (based on the images in the OP) I'd recommend you consider lengthening the gear and brake cable outers by the bar. They look short and the radii of their curves appear very low.

 

[ilcaccillo]

The crankset I have it's a Miranda Alfa 1, and a 38T direct Mount Chainring.

I've seen a couple of "narrow wide chainrings" for direct mount, although they seem to use a different splinder than than what's used in my Miranda crankset,
unfortunatelly Miranda doesn't have a "narrow wide" offering

Well I might change the crack bracket and crankset for a model that gives more options and flexibility of chainring choices.
Maybe a more universal system.

Need to figure it out if new models will fit in this older frame.
I don't know the common measures for the bracket frame hole and lenght

 

[chriswoody]

Just a few thoughts, firstly the narrow wide chainring on a 1x system is only part of the solution. The rear mech will also have narrow/wide jockey wheels as well as a clutch system. All of this combined helps keep the chain in place, wether having just a narrow wide chainring is sufficient, I really don't know.

Bottom Bracket wise, the diameter of the shell will be universal, the threads should be the common English standard. In order to fit a modern narrow wide chainset I expect you'll need to use external bearing bottom bracket like Shimano Hollowtech 2. If you have the common English thread, then it's just a case of measuring the shell width, 68 & 74mm are the two standard sizes, and purchase the appropriate width one. On my Kona I have a 68mm wide bottom bracket shell, into which I have a FSA BB, (however, Hollowtech 2 will also fit). Then I have a RaceFace Aeffect single ring crankset. So I suspect looking at your pictures that it's more than possible to fit a narrow wide chainset. The real question is wether it will work and wether it's worth the expense.

 

[Ajax Bay]

I might change the crack bracket and crankset for a model that gives more options and flexibility of chainring choices.
Maybe a more universal system.

If you want to go this way (and the reasons you list are entirely rational) then I think it's reasonable to assume that the bottom bracket is square taper and normal width (68mm)/threads. If so then a BB-UN55 is the best option. And a wide range of square taper chainsets.

 

[figbat]

If you have a square taper on there already and it is in good condition then all you need is replacement crank arms. I did exactly this on my MTB-to-gravel bike; I pulled off the old arms and fitted this crankset and this chainring.

 

[ilcaccillo]

Bottom Bracket wise, the diameter of the shell will be universal, the threads should be the common English standard. In order to fit a modern narrow wide chainset I expect you'll need to use external bearing bottom bracket like Shimano Hollowtech 2. If you have the common English thread, then it's just a case of measuring the shell width, 68 & 74mm are the two standard sizes, and purchase the appropriate width one. On my Kona I have a 68mm wide bottom bracket shell, into which I have a FSA BB, (however, Hollowtech 2 will also fit). Then I have a RaceFace Aeffect single ring crankset. So I suspect looking at your pictures that it's more than possible to fit a narrow wide chainset.

Thank you so much for the info chriswoody, I will measure the shell width.
With all your help I'm learning a lot also along the way.
thank you so much for the recomendations of the Hollowtech 2 and the FSA BB

 

[ilcaccillo]

If you have a square taper on there already and it is in good condition then all you need is replacement crank arms. I did exactly this on my MTB-to-gravel bike; I pulled off the old arms and fitted this crankset and this chainring.

If seems to be a square taper yes, but I'm still new to the different standards, sizes and threads. I keep learning with your input and reading articles when a new thing comes up. Also, I'm from Portugal, so I'm also learning the technical names in English for the parts.

But yes, it seems a square taper, I will unmount the crankset arms so I can have a better look and take some photos.
The bracket is in really good condition, actually everything in the bike is in very good condition.
Your solutions seems quite nice and inexpensive.

Do you know if theres any standard sizes for the distance between those 4 holes in the crankset? (the 4 holes where a chainring will mount)

"Miranda" has something similar to the crankset your showed and it's a local company so it's easier to get the part internally,
but the 4 holes might not have the same distancing:

 

[Ajax Bay]

AASSIA BCD

 

[ilcaccillo]

Thanks,
also found a nice article from Wolf Tooth on BCD 4 and 5 bolt sizes

https://www.wolftoothcomponents.com/pages/how-to-measure-bolt-circle-diameter-bcd